Development Of Simulated Reaction System For NH₃-SCR Of Diesel Engine And Study On Fe/V₂O₅/TiO₂ Catalysts

As one of the most effective approaches, NH₃-SCR is widely used to abate NO_X emissions from diesel engine abroad. To further study NH₃-SCR system for diesel engine which will meet the stricter regulated standards, the reaction test system to simulate diesel engine exhausts was developed. Moreover, aimed at the common shortcomings of high toxicity and environmental pollution, the investigations have been conducted on the relationships among the vanadium catalyst compositions, preparation and performance, and then series of environmental friendly iron catalysts containing low vanadium have been researched. The main contents of the dissertation are as follows:1. The advanced reaction test system could simulate the NH₃-SCR reaction in diesel engine exhausts, and the detection limits for NO_X, NH₃, CO and HC all are 3ppm except 0.1% for CO₂. The system was able to achieve real-time dynamic collection and data processing;2. Combined with XRD, DTG, RAMAN, BET and EDS analytical techniques, the effects of several parameters, including main catalyst, promoter, coating, carrier and preparation technics, on catalytic reaction performance was performed with the reaction test system. The optimized catalyst prescriptions and preparation were put forward. The results indicated that the cordierite catalysts, which were prepared by multi-step soaking and contained the structure additive, presented the high catalytic activities. The experimental data showed that under the condition of the NO/NH₃ molar ratio of 1:1 and the velocity of 40000h-1, the NO reduction efficiency of catalyst was up to 90%, meanwhile, NH3 was controlled effectively.3. According to the avirulent request for NH₃-SCR catalyst in the world, the new environment friendly catalyst containing iron and low vanadium were developed. With this catalyst, the favorable"temperature window"of high catalytic activity could be obtained and the outstanding NO abatement was attained. In addition, the reaction mechanism of iron-SCR catalyst was given a preliminary explanation. The overall work above will benefit the promotion of SCR technology and the development of new environment friendly SCR catalyst.